The present invention relates to a new and improved apparatus for controlling the cooling of a strand departing from a continuous casting mold wherein the quantities of cooling water impinging the surface of the strand at the individual cooling zone sections are adjustable and at the beginning of the casting operation there are determined by a computer reference or rated values of such quantities of cooling water as a function of the chemical or metallurgical composition of the strand material, strand cross-section and the desired casting speed, and during casting such rated values are changed as a function of the travel time of imaginary strand sections from the mold up to a relevant section of the cooling zone.
It is conventional practice during the continuous casting of steel to control the quantities of the cooling agent, typically water, at the so-called secondary cooling zone which follows the continuous casting mold. Consequently, the quantities of cooling water are adjusted at the individual zones, also referred to in the art as the cooling zone sections or regions, in such a way that there is realized an approximately constant surface temperature at the strand during its solidification. The values of the quantitative amounts of cooling water which should be set prior to the start of casting are determined by a computer as a function of the composition of the strand material, the strand cross-section and the desired casting time. The quantities of water introduced into the individual regions or zones of the secondary cooling zone becomes that much smaller the farther the relevant zone is located from the mold, since the thickness of the skin of the strand increases with increasing distance from the mold, whereby in the same way the heat conduction resistivity or resistance also increases. If during casting there occur changes in the above-mentioned influencing factors, especially the casting speed, then these changes can be taken into account to a certain degree. This occurs for instance in that the strand is subdivided into imaginary sections and there is fixed the time which the sections require for the travel from the mold up to the cooling device. As a function of this time, the computer selects from a prescribed curve the appropriate new quantity of cooling agent.
In practice, this technique has been associated with considerable drawbacks since it does not take into account the actual cooling and solidification conditions, and it is for this reason that the desired heat transmission rates cannot be controlled in accordance with the actual conditions. In order to nonetheless insure that in any event sufficient cooling water will be infed, the quantitative amount of such cooling water is generally selected to be greater than actually necessary. This of course results in increased consumption of water and at the same time can lead to impairment of the surface properties of the casting.